Process and apparatus for producing carbon black



March 31, 1931. c. MATLOCK PROCESS AND APPARATUS FOR PRODUCING CARBON BLACK Filed March 14, 1921 INVENTOZ /4M ATTORNEY Patented Mar. 31, 1931 "UNITED STATES PATENT orrlca OHAUNOEY MATLOO'K, OF BROOKLYN, NEW YORK, ASSIGNOR TO MONROE-LOUISIANA CARBON COMPANY, 01 MONROE, LOUISIANA, A CORPORATIOR O18 DELAWARE PROCESS AND APPARATUS FOR PRODUCING CARBON BLACK Application filed March 14, 1921. Serial No. 452,292.

The present invention relates to the production of carbon black and more particularly to a process and apparatus for the production of carbon black by the partial com- 5 bustion of hydrocarbons.

Carbon black has been customarily produced heretofore by burning natural gas or other gaseous hydrocarbons in a large number of small burners in such a manner that the outer part of the flame received sufficient air for complete combustion while the inner portion of the flame was subjected to a dissociating temperature and insuflicient air for complete combustion. Through the dissociation and partial combustion of the hydrocarbons in the interior of theflame, a small amount of free carbon, together with some incompletely dissociated hydrocarbons, was formed. This carbon was collected, and

the further oxidation of the hydrocarbons and destruction of the carbon formed, through the access of air to the upper part of the flames, was prevented by contacting and chilling the flames with a cooled plate 55 or other cold surface on which the flames were caused to impinge. The production of carbon black in this manner not only involved a large and extensive installation for the burning of the gases in quantities suflicient to permit of commercial operation but also afiorded a low efiiciency in the production of carbon and a very imperfect control of the process owing to the difficulty of regulating the conditions in the large number of small flames. Because of this imperfect control and of the natural tendency toward the formation of incompletely dissociated hydrocarbons, with the resulting formation of oily and tarry products in the carbon deposited on 40 the chilled plate, these rocesses have failed to produce a carbon 0 the quality desired for many purposes. Other processes have been pro osed for the production of hydrocarbons, ut have failed to give the desired 46 results owing to the failure to provide a sufficiently accurate control of the temperature and other conditions governing the quantity and quality of carbon produced.

An object of the present invention is to provide an improved and eficient process for making a carbon black of excellent quality.

Another object of the invention is to pro? vide a process in which the conditions governing the production of carbon black by the partial combustion of hydrocarbons may be accurately and readily controlled.

A further object of the invention is to provide an improved and eficient apparatus for the production of carbon black in which the conditions of combustion of hydrocarbons may be accurately and readily controlled.

With these and other objects in view the invention comprises the process and apparatus describedin the following specification and defined in the claims.

The various features of the invention are illustrated in the accompanying drawings in which 1 Fig. 1 is a View, partly in vertical section, of the preferred form of an apparatus for operating the present invention, and,

Fig. 2 is a view in elevation of a modification of the furnace forming part of the apparatus shown in Fig. 1.

In the present invention the hydrocarbons are burned in a comparatively large flame in which a complete and thorough mixture of air for partial combustion is permitted, and the degree of oxidation of the hydrocarbons is controlled by regulating the air supply and .the temperature conditions throughout the flame to break up or dissociate and partially oxidize all of the hydrocarbons and form a maximum of free carbon particles. To this end a regulated quantity of hydrocarbon gases is supplied to the lower part of a closed combustion chamber through a number of burners and isimixed with a regulated supply of air which is forced into the furnace below the burners by means of a blower or other means for supplying air. Upon passing upwardly in the furnace the air and gas enter a body or blanket of hot products of combustion and burning gases which is maintained in the combustion chamber extending u wardly from a short distance above the urners. The air and hydrocarbons are partially mixed before entering this body of hot products of combustion and upon entering the hot gases, the mixture of the hydrocarbons with the air is completed and the hydrocarbons are ignited and burned in an atmosphere of the hot products of combustion. As the burning gases reach the upper part of the combustion chamber the dissociation or breaking up and the partial combustion of the hydrocarbons will have been completed and the hot gases and suspended carbon are, thereupon, rapidly removed and quickly chilled to prevent any further heating and re-oxidation of the carbon already formed. The carbon is separated or filtered from the cooled gases which are thereafter permitted to escape into the atmosphere. The quantity and the quality of the carbon black produced are dependent to a considerable extent upon the temperature conditions maintained in the furnace and upon the manner and time of combustion or treatment in the furnace. To control these conditions so as to obtain the maximum yield of carbon black of the desired quality, a small portion of the hotproducts of combustion are permitted to escape from the top of the furnace and the rate of escape of the gases is controlled to give the desired temperature and velocity conditions in the furnace.

Referring more particularly to the accompanying drawings a regulated supply of gaseous hydrocarbons is admitted to a furnace 1 through a supply pipe 2 and a controlling valve 3 and is distributed throughout the lower part of the furnace by a number of burners 4, Fig. 1 A regulated supply of air suflicient to effect only a partial combustion of the hydrocarbons is forced by means of a fan or blower 5 through a supply conduit 6 and controlling valve 7 into the furnace l at a short distance below the burn ers 4. As the air passes upwardly into contact with the streams of hydrocarbon gases issuing from the burners 4, it is permitted to mix with the hydrocarbons but the temperature and velocity of the air and gases are so controlled in relation to the rate of mixture that combustion of the gases does not begin until the gases reach a body or blanket 8 of hot or incandescent products of combustion -maintained into the upper part of the furnace from a short distance above the burners 4. As the upwardly passing gases and air enter the blanket or body of hot burning gases and products of combustion the mixing of the gas and air is completed and the mixture is ignited and burned within and surrounded by the hot gases. Through this manner of treatment the hydrocarbons are subjected in the body of hot gases to a substantially uniform temperature throughout unaffected by local chilling or cooling by cold surfaces or cold gases. Any tendency to local overheating of the gases, due to imperfect mixing of the air and hydrocarbons and consequent presence in parts of the flame of air in quantities sufiicicnt to effect complete combustion of the hydrocarbons, is counteracted by the mass of hot products of combustion which surround, and are mixed with, the hydrocarbon mixture. By maintaining uniform and accurately controlled conditions in the furnace, the quantity of air supplied may be reduced to the minimum required for the dissociation of the hydrocarbons and the oxidation of the hydrogen set free and of such an amount of carbon as is required to maintain the proper temperature and equilibrium conditions in the flame.

The temperature which is attained in the burning gases may be measured by means of a thermocouple 9 and a suitable galvanometer, not shown, or by other means and the temperature and other conditions of treatment are controlled to a certain extent by regulating the withdrawal of gases from the upper part of the furnace. The major portion of the gases is withdrawn through an outlet conduit 10 and damper 11 by means of a fan 12 which balances the draft of the blower 5 and forces the gases and carbon to a carbon filtering or separating device.

To obtain a quickly responsive control of the furnace conditions without adjusting the driving of the fan 12 and thereby interfering with the carbon filtering or separating-operation, a portion of the hot gases are permitted to escape through an outlet or exhaust opening 14 extending from the upper part of the furnace above the outlet pipe 10. The rate of escapebfgases through the opening 14; is controlled by means of a sliding damper 16 to regulate the quantity and velocity and other conditions in the hot gases 8 and to maintain the blanket of gases 8 at the desired distance above the burners 4, thereby regulating the flame conditions in the furnace. Through the balanced draft obtained by means of the blowers 5 and 12, the gases within the furnace 1 are maintained at substantially atmospheric, or slightly above atmospheric, pressure and the quantity of gases which are permitted to escape through the opening 14 is very small as compared with the quantity withdrawn through the opening 10. The small less in carbon resulting through the escape of these gases is more than compensated by the increased efiiciency of production and improved quality of the temperature may be measured byineans of carbon obtained throu h the proper regulation of the furnace con 'tions. f

To reduce this loss still further, however, the furnace arrangement shown in Fi 2 may be employed. In this arrangement t e withdrawal pipe 10 is positioned at a considerable distance below the top of the furnace thereby providing a settlin chamber above the pipe 10 and permitting t e major portion of the carbon to settle out of the escaping gases before they leave the furnace and thereby permittin them to be drawn into the pipe or pipes 18 of com aratively small di-' ameter and are chilled y means of water s rays from spray pipes 20 or by other suitable cooling means to a temperature at which the gases ma be filtered or otherwise separated from t e hot gases. The withdrawal of the gaseous products through the pipe 10 and the chilling in the pipes 18 is accomplished very rapidly while the gases are passing through the pipes at a high velocity and any reaction of the gases after leaving the furnace 1 is thereby avoided.

From the pipes 18 the gas and carbon pass through a connecting pipe 22, in which their a thermometer 24, to a carbon collecting or separating apparatus 26, a separator of the bag filter type being illustrated in the drawings. Upon entering the separator 26 thegases are caused to pass upwardly through filtering bags 28 and are withdrawn through an outlet pipe 30 and controlling valve 32 by means of a fan 34.

The filtering bags 28 are fastened at their lower ends to a horizontal dividing plate 36 provided with openings 38 which open into the bags 28. The upper parts of the bags are supported on blocks 40 which are suspended from a frame 42. The frame 42 is in turn supported eccentrically from a shaft 44 extending through the top of the furnace and operable by means of a crank 46 in such a manner as to give the top of the bags a small circulatory movement and to throw chains 48 depending from the blocks 40 into contact with the inner walls of the bags to detach the carbon deposited thereon. The detached carbon thereupon falls into a hopper 50 at the lower part of the separator and may be removed through an outlet 52 upon withdrawing a slide 54. It will be apparent that other types of carbon separating devices may be employed although bag filters are preferred.

different temperatures,

"Different types of gases require somewhat gas mixtures and other conditions of operations and the dimensions ofthe furnace and manner of operating the apparatus may be varied to suit the particular requirements of the gas operated upon. In treating a Louisiana natural gas for instance, a furnace of about 6 ft. in diameter by from 15 to 25 ft. in height has been found to give good results. The flame in the furnace is kept at a glowing red heat but an 'excessively'high temperature is to be avoided.

The color of the flame escaping through the outlet 14 may also be used to serve as an indication of the conditions existing in the furnace and, taken in connection with the temperature and appearance of the flame within the furnace will serve as a guide to the proper adjustment of the damper 16 to maintain those conditions, in any particular case, which give the desired results. The eduction or withdrawal pipe 10 for a. furnace of the above size will ordinarily be within from 6 to 10 inches in diameter and the gases in passing through the cooling pipe 18 are cooled to temperatures of from 180 to 220 F. before entering the bag filters.

By means of the above described process and apparatus a very accurate control of the process may be obtained. It will be obvious that changes in the size and proportions of the furnace, in the type of carbon collector used and in other minor details may be made to suit difierent conditions without departting from the broader features of the inven Having described the invention, what I claim as new is:

1. An apparatus for roducing carbon black which comprises a urnace, means for supplying air and hydrocarbons in regulated quantities to said furnace under pressures slightly above atmospheric, means for positively withdrawing products of partial combustion from said furnace, means independent of said supply and withdrawing means for regulating the flame conditions in the said furnace, said means for regulating the flame being positioned above said withdrawal products of combustion from said chamber,

and means for separating and isolating the carbon black from the said products of combustion;

3. A process of producing carbon black combustion to said furnace to form products of combustion at a slightly higher rate than they are withdrawn from said furnace, and permitting the excess products of combustlon to escape from said furnace at approximately atmospheric pressure.

4. A process of producing carbon black which comprises forcing hydrocarbons and air in insufiicient quantity to completely burn said hydrocarbons to a combustion chamber, incompletely burning said mixture of air and hydrocarbons in said combustion chamber to form carbon suspended in gaseous products of partial combustion, withdrawing the products of combustion from said combustion chamber at a rate slightly less than their rate of combustion, isolating the carbon from said withdrawn'products of combustion, and permitting the excess of products of combustion to escape from said combustion chamber at approximately atmospheric pressure. 7

5. A process of producing carbon black which comprises supplying hydrocarbons and air in insuflicient quantity to completely burn said hydrocarbons to the lower portion of a combustion chamber, incompletely burning said mixture of air and hydrocarbons in said combustion chamber to form carbon suspended in gaseous products of partial combustion, withdrawing the products of combustion from the upper portion of said combustion chamber at a rate slightly less than the rate of formation of said products in said combustion chamber, removing the carbon from said withdrawn products of combustion, and permitting the excess of products of combustion to escape from said combustion chamber ata level above that of withdrawal.

6. A process of producing carbon black which comprises supplying hydrocarbons and air in proportion to incompletely burn said hydrocarbons to the lower portion of a combustion chamber, incompletely burning said hydrocarbons while passing upwardly through said combustion chamber to form a suspension of carbon in products of incomplete combustion, withdrawing the products of combustion and suspended carbon from the upper portion of said combustion chamber at a rate slightly less than the rate of their formation, removing the carbon from In testimony whereof, I aflix my signature. I

CHAUNOEY MATLOCK.

the withdrawn products of combustion, and

permitting the excess of products of combustion to pass freely to the atmosphere above the withdrawal level.

7 An apparatus for tproducing carbon black which comprises a urnace, means for 

